Couldn't find User with 'id'=2

<% if current_user %>
  Signed in as <strong><%= current_user.name %></strong>!
  <%= link_to "Sign out", signout_path, id: "sign_out" %>
 <% else %>
<% end %>

def current_user
 @current_user ||= User.find(session[:user_id]) if session[:user_id]
 end